Methods for preparing epoxides by olefin epoxidation

Abstract

This invention discloses a method for preparing epoxides through the epoxidation of olefins. The method includes contacting H₂O₂ with an olefin in a solvent in the presence of a hierarchical porous titanium-silicon molecular sieve catalyst, wherein the bulk density of the hierarchical porous titanium-silicon molecular sieve is 3.0–4.0 g / mL. This method, used in the epoxidation reaction of olefins involving H₂O₂, exhibits high activity, good stability, and good selectivity.

Description

Technical Field

[0001] This invention belongs to the field of olefin production epoxide technology, specifically, it relates to a method for preparing epoxides by olefin epoxidation in the presence of hydrogen peroxide. Background Technology

[0002] Titanium silicate molecular sieve TS-1 is an excellent catalyst for the epoxidation of olefins. With the participation of hydrogen peroxide, certain olefins, such as propylene and allyl chloride, have been industrially produced at relatively low temperatures.

[0003] The traditional hydrothermal synthesis method was used to prepare titanium-silicon molecular sieve TS-1. The synthesis conditions were harsh, and the resulting titanium-silicon molecular sieve TS-1 had a small specific surface area and contained only micropores and intercrystalline macropores, but no mesoporous channels.

[0004] The preparation of TS-1 molecular sieves with microporous and mesoporous composite hierarchical channels has been a long-standing research hotspot. One research approach is to utilize pre-formed molecular sieve precursors with mesoporous channel structures but poor crystallinity, and then convert them in situ into molecular sieves with a unique MFI structural framework while retaining mesopores. HMS molecular sieves possess such a structure, featuring worm-like channels, hexagonal crystals, and interconnected pores. HMS molecular sieves have relatively thick pore walls and good hydrothermal stability. Various metal ions can be introduced for modification during the synthesis of HMS molecular sieves, including Ti. Extensive research has been conducted on modified Ti-HMS molecular sieves. Although Ti-HMS molecular sieves can be applied to the epoxidation of olefins, they generally suffer from low conversion rates, poor selectivity, and poor hydrothermal stability. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for preparing epoxides through olefin epoxidation. This method is used for olefin epoxidation reactions involving H2O2 and features high activity, good selectivity, and few byproducts.

[0006] The first aspect of the present invention provides a method for preparing epoxides by epoxidation of olefins, wherein H2O2 is contacted with olefins in a solvent in the presence of a catalyst, wherein the catalyst is a hierarchical porous titanium-silicon molecular sieve with a bulk density of 3.0 to 4.0 g / mL.

[0007] Furthermore, the olefin is selected from at least one of propylene, chloropropylene, butene, and cyclohexene.

[0008] Furthermore, the solvent is selected from at least one of acetone, methanol, ethanol, isopropanol, tert-butanol, and acetonitrile.

[0009] Furthermore, the mass concentration of the H2O2 is 15% to 60%.

[0010] Furthermore, the molar ratio of olefin to H2O2 is 2.0 to 6.0:1, and the molar ratio of solvent to olefin is 1.0 to 4.0:1.

[0011] Furthermore, the reaction temperature is 30–60℃, and the liquid hourly space velocity of H₂O₂ is 0.5–3.0 h⁻¹. -1 .

[0012] Furthermore, the pore distribution of the multi-level porous titanium-silicon molecular sieve is as follows: pores with a diameter less than 2.0 nm account for 20% to 40% of the total pore volume, pores with a diameter of 2.0 to 5.0 nm account for 10% to 30% of the total pore volume, pores with a diameter of 5.0 to 20.0 nm account for 25% to 50% of the total pore volume, and pores with a diameter greater than 20.0 nm to 50 nm account for less than 10% of the total pore volume, preferably 4% to 9%.

[0013] Furthermore, the multi-level channels include micropores and mesopores. Micropores refer to pores with a diameter of 0.5 to 0.8 nm, and mesopores refer to pores with a diameter of 2.0 to 50.0 nm.

[0014] Furthermore, the average pore size of the molecular sieve is 2.5–3.8 nm.

[0015] Furthermore, the specific surface area of ​​the molecular sieve is 450–550 m². 2 / g, total pore volume is 0.25~0.55cm³ 3 / g, preferably 0.31~0.55cm 3 / g, with micropore volume of 0.15–0.45 cm³. 3 / g, preferably 0.20~0.45cm 3 / g.

[0016] Furthermore, the preparation method of the multi-level porous titanium-silicon molecular sieve includes the following steps:

[0017] (1) A gel is obtained by mixing silicon source, first template agent, anhydrous ethanol and water, adjusting the pH of the gel to 8-12 and aging it to obtain the precursor material.

[0018] (2) Mix the precursor material obtained in step (1), titanium source, second template agent and water, and crystallize to obtain intermediate crystalline material;

[0019] (3) The intermediate crystalline material obtained in step (2) is calcined to obtain the multi-level porous titanium silicon molecular sieve.

[0020] Further, in step (1), the molar ratio of silicon source (SiO2), first template agent, anhydrous ethanol and H2O is 1:(0.1-0.5):(3-10):(20-100).

[0021] Further, in step (1), the silicon source is selected from at least one of silica sol, solid silicon oxide, silica fume or silicate ester.

[0022] Further, in step (1), the first template agent is selected from at least one of dodecylamine, tetradecylamine, hexadecylamine or octadecylamine.

[0023] Furthermore, in step (1), the aging is carried out under stirring, the aging temperature is 10-40°C, and the time is 12-36 hours.

[0024] Furthermore, in step (1), the pH can be adjusted by adding ammonia.

[0025] Further, in step (1), after the aging step is completed, the precursor material product can be separated from the obtained mixture by any conventionally known separation method, such as filtration, washing, and drying. Here, the filtration, washing, and drying can be carried out in any manner conventionally known in the art. The drying temperature can be selected from 80 to 200°C, preferably 100 to 150°C; the drying time is 2 to 24 hours, preferably 5 to 10 hours. The drying can be carried out under normal pressure or under reduced pressure; to save energy, normal pressure is usually chosen.

[0026] Further, in step (2), the molar ratio of the precursor material (SiO2), the titanium source (TiO2), the second template agent, and water is 1:(0.02-0.1):(0.1-0.35):(10-50).

[0027] Further, in step (2), the titanium source is selected from at least one of tetraalkyl titanate or titanium halide.

[0028] Further, in step (2), the second template agent is selected from at least one of tetrapropylammonium bromide, dimethylamine, trimethylamine, ethylenediamine, hexamethylenediamine, cyclohexylamine, isopropylamine, diethylamine, triethylamine or n-butylamine.

[0029] Further, in step (2), the crystallization conditions are as follows: the crystallization temperature is 130-200℃, and the crystallization time is 12-100 hours. Preferably, the crystallization temperature is 160-180℃ and the crystallization time is 24-72 hours.

[0030] Further, in step (2), after the crystallization step is completed, the intermediate crystalline material product can be separated from the obtained mixture by any conventionally known separation method, such as filtration, washing, and drying. Here, the filtration, washing, and drying can be carried out in any manner conventionally known in the art. The drying temperature can be selected as 80–200°C, preferably 100–150°C; the drying time is 2–24 h, preferably 5–10 h. The drying can be carried out under normal pressure or under reduced pressure; to save energy, normal pressure is usually chosen.

[0031] Furthermore, in step (3), the calcination conditions are as follows: the calcination temperature is 400-550℃, the calcination time is 5-10 hours, and the atmosphere is an oxygen-containing gas (such as air).

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] The method of this invention uses H2O2 and olefins as raw materials and multi-level porous titanium-silicon molecular sieves as catalysts. The catalyst has a large specific surface area, suitable bulk density, and a specific pore structure that is suitable for olefin epoxidation reactions with H2O2 participation. In this type of reaction, it has the characteristics of high activity, good selectivity, and few by-products.

[0034] The preparation method of this invention for a hierarchical porous titanium-silicon molecular sieve involves synthesizing a mesoporous silicon precursor material using a first template agent, followed by liquid-phase hydrothermal crystallization using a second template agent and a titanium source. This method utilizes the weak guiding ability of the microporous small-molecule organic amine template agent during the crystallization process, allowing the mesoporous precursor to be transformed in situ into a monolithic TS-1 molecular sieve. This hierarchical porous titanium-silicon molecular sieve retains most of the mesoporous structure of the precursor while generating the microporous structure unique to the MFI structure during crystallization. These specific structural characteristics give this molecular sieve advantages such as good catalytic activity, faster material diffusion rate, more stable catalyst performance, and fewer byproducts in the olefin epoxidation reaction involving H2O2. Attached Figure Description

[0035] Figure 1 The XRD pattern of the multi-level porous titanium-silicon molecular sieve prepared in Example 1 of this invention;

[0036] Figure 2 The N2 adsorption-desorption curves of the multi-level porous titanium-silicon molecular sieve prepared in Example 1 of this invention are shown. Detailed Implementation

[0037] The technical solutions of the present invention will now be clearly and completely described with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0038] The present invention uses the following equipment to characterize the prepared multi-level porous titanium-silicon molecular sieve. The following examples all use the same characterization equipment and testing methods.

[0039] In this invention, a Rigaku-Ultima X-ray diffractometer from Japan was used for molecular sieve crystal phase analysis. The XRD test conditions were: CuKα radiation, wavelength λ = 0.15432 nm; X-ray diffraction pattern scanning range 2θ = 5° to 50°, scanning speed 10° / min, working voltage 40 kV, and current 40 mA.

[0040] In this invention, the average pore size and total pore volume of the molecular sieve are determined by N2 physical adsorption. The test method is as follows: The specific surface area (BET) and pore volume of the sample are analyzed using an Autosorb-I type automatic adsorption specific surface area and porosity analyzer from Quantachrome, USA, wherein the cold trap is liquid nitrogen and the adsorption medium is high-purity nitrogen gas; the low-pressure section of the adsorption isotherm is analyzed using the adsorption isotherm equation of the HK model to obtain the pore size distribution curve of the molecular sieve; the specific surface area and pore volume of the molecular sieve are calculated by the BET method and the t-plot method, respectively.

[0041] In this invention, gas chromatography is used to analyze the products. A certain amount of the reaction mixture is injected into the gas chromatograph through the injection port, flows through the chromatographic column, is detected by FID, and is quantitatively analyzed by the external standard method. The gas chromatograph used is an Agilent 7890 gas chromatograph, and the analytical column used is an INNOWAX column.

[0042] The formulas for calculating conversion rate and selectivity in the application examples of this invention are as follows:

[0043] Olefin conversion rate x = (mass percentage of each chromatographic product and byproduct) / (mass percentage of each chromatographic product and byproduct + mass percentage of olefin) × 100%;

[0044] The selectivity of epoxidation products S = mass percentage of epoxidation products / (mass percentage of each chromatographic product and byproduct + mass percentage of olefins) × 100%;

[0045]

[0046]

[0047] Olefin conversion rate X = H2O2 conversion rate X H2o2 ×H2O2 effective utilization rate U H2O2 / Olefin to H2O2 molar ratio × 100%.

[0048]

Example 1

[0049] 38.50 g of 30% silica sol, 53.13 g of anhydrous ethanol, and 11.48 g of tetradecylamine were mixed and stirred at room temperature. 173.08 g of H2O was added to achieve a molar ratio of SiO2, tetradecylamine, ethanol, and H2O of 1:0.3:6:50 in the gel. The pH of the gel was adjusted to 9.0, and the mixture was stirred and aged at 20°C for 20 hours. The resulting gel was filtered, washed with deionized water, and dried at 120°C for 5 hours to obtain the precursor silicon material.

[0050] 1.63 g of tetrabutyl titanate, 0.87 g of dimethylamine, 2.81 g of n-butylamine, and 69.30 g of H₂O were mixed, and precursor silicon material was added to achieve a molar ratio of SiO₂, TiO₂, (dimethylamine + n-butylamine), and water of 1:0.025:0.30:20. The mixture was crystallized at 180 °C for 48 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 500 °C for 5 hours to obtain a hierarchical porous titanium-silicon molecular sieve.

[0051] The XRD characterization results of the above molecular sieves are as follows: Figure 1 As shown, the N2 physical adsorption characterization results are as follows: Figure 2 As shown. From Figure 1 It can be seen that this molecular sieve is a mesoporous titanium silicate molecular sieve and has an MFI topology. From Figure 2 Hysteresis loops were observed, confirming the presence of mesopores. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 31% of the total pore volume; pores with diameters between 2.0 and 5.0 nm accounted for 25%; pores with diameters between 5.0 and 20.0 nm accounted for 35%; and pores larger than 20.0 nm to 50.0 nm accounted for 9%. The average pore diameter was 2.9 nm, and the total pore volume was 0.48 cm³. 3 / g, micropore volume is 0.33cm³ 3 / g, specific surface area is 505m² 2 / g. The bulk density of the molecular sieve is 3.5 g / mL.

[0052]

Application Example 1

[0053] 1 g of the multi-level porous titanium-silicon molecular sieve prepared in Example 1 was added to a fixed-bed reactor. A propylene:H₂O₂ molar ratio of 3.5:1 and an acetone:propylene molar ratio of 1.5:1 were introduced. The H₂O₂ concentration was 30%, and the space velocity (H₂O₂) was 3.0 h⁻¹ (based on pure H₂O₂). -1 The reaction temperature is 45℃.

[0054] The reaction products were sampled and analyzed by gas chromatography. The results showed that the selectivity of propylene oxide (based on propylene) was 97.60%, the conversion rate of H2O2 was 93.28%, and the effective utilization rate of H2O2 was 95.54%.

[0055]

Example 2

[0056] 38.50 g of 30% silica sol, 70.84 g of anhydrous ethanol, and 14.25 g of dodecylamine were mixed and stirred at room temperature. 50.25 g of H₂O₂ was added to achieve a molar ratio of SiO₂, dodecylamine, ethanol, and H₂O of 1:0.4:8:80 in the gel. The pH of the gel was adjusted to 11.0, and the mixture was stirred and aged at 15°C for 32 hours. The resulting gel was filtered, washed with deionized water, and dried at 120°C for 8 hours to obtain the precursor silicon material.

[0057] 2.61 g of tetrabutyl titanate, 0.57 g of trimethylamine, 2.81 g of n-butylamine, and 138.60 g of H₂O were mixed, and precursor silicon material was added to achieve a molar ratio of SiO₂, TiO₂, (trimethylamine + n-butylamine), and water of 1:0.04:0.25:40. The mixture was crystallized at 170 °C for 60 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 550 °C for 5 hours to obtain a hierarchical porous titanium-silicon molecular sieve.

[0058] The XRD patterns of the above molecular sieves and Figure 1 Similarly, it is a mesoporous titanium silicate molecular sieve with an MFI topology. The N2 physisorption characterization results of this molecular sieve are similar to... Figure 2 Similarly, hysteresis loops were observed, confirming the presence of mesopores. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 37% of the total pore volume; pores with diameters between 2.0 and 5.0 nm accounted for 26%; pores with diameters between 5.0 and 20.0 nm accounted for 30%; and pores larger than 20.0 nm to 50.0 nm accounted for 7%. The average channel diameter was 3.8 nm, and the total pore volume was 0.50 cm³. 3 / g, with a micropore volume of 0.32cm³. 3 / g, specific surface area is 453m² 2 / g. The bulk density of the molecular sieve is 3.2 g / mL.

[0059]

Application Example 2

[0060] 1 g of the molecular sieve prepared in Example 2 was added to a fixed-bed reactor. The reactor was bubbled with a butene:H₂O₂ molar ratio of 6.0:1, an acetonitrile:butene molar ratio of 2.0:1, and an H₂O₂ concentration of 27.5%. The space velocity (H₂O₂) was 1.0 h⁻¹ (based on pure H₂O₂). -1 The reaction temperature is 50℃.

[0061] The reaction products were sampled and analyzed by gas chromatography. The results showed that the selectivity of epoxidized butene (based on butene) was 85.03%, the H2O2 conversion rate was 95.73%, and the effective utilization rate of H2O2 was 98.64%.

[0062]

Example 3

[0063] 38.50 g of 30% silica sol, 61.99 g of anhydrous ethanol, and 20.50 g of hexadecylamine were mixed and stirred at room temperature. 146.30 g of H2O was added to achieve a molar ratio of SiO2, hexadecylamine, ethanol, and H2O of 1:0.5:7:50 in the gel. The pH of the gel was adjusted to 11.5, and the mixture was stirred and aged at 23°C for 36 hours. The resulting gel was filtered, washed with deionized water, and dried at 120°C for 9 hours to obtain the precursor silicon material.

[0064] 3.92 g of tetrabutyl titanate, 1.05 g of diethylamine, 0.87 g of ethylenediamine, and 173.25 g of H2O were mixed, and precursor silicon material was added to achieve a molar ratio of SiO2, TiO2, (diethylamine + ethylenediamine), and water of 1:0.06:0.15:50. The mixture was crystallized at 175 °C for 72 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 480 °C for 6 hours to obtain a hierarchical porous titanium-silicon molecular sieve.

[0065] The XRD patterns of the above molecular sieves and Figure 1 Similarly, it is a mesoporous titanium silicate molecular sieve with an MFI topology. The N2 physisorption characterization results of this molecular sieve are similar to... Figure 2 Similarly, hysteresis loops were observed, confirming the presence of mesopores. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 25% of the total pore volume; pores with diameters between 2.0 and 5.0 nm accounted for 30%; pores with diameters between 5.0 and 20.0 nm accounted for 39%; and pores larger than 20.0 nm to 50.0 nm accounted for 6%. The average channel diameter was 3.6 nm, and the total pore volume was 0.52 cm³. 3 / g, micropore volume is 0.28cm³ 3 / g, specific surface area is 481m² 2 / g. The bulk density of the molecular sieve is 3.4 g / mL.

[0066]

Application Example 3

[0067] 1 g of the molecular sieve prepared in Example 3 was added to a fixed-bed reactor. A cyclohexene:H₂O₂ molar ratio of 5.0:1 and a tert-butanol:cyclohexene molar ratio of 4.0:1 were introduced. The H₂O₂ concentration was 40%, and the space velocity (H₂O₂) was 0.5 h⁻¹ (based on pure H₂O₂). -1 The reaction temperature is 60℃.

[0068] The reaction products were sampled and analyzed by gas chromatography. The results showed that the selectivity of cyclohexene epoxidation (based on cyclohexene) was 93.38%, the H2O2 conversion rate was 94.66%, and the effective utilization rate of H2O2 was 93.50%.

[0069]

Example 4

[0070] 11.55 g of silica, 88.55 g of anhydrous ethanol, and 8.74 g of octadecylamine were mixed and stirred at room temperature. 103.95 g of H2O was added to achieve a molar ratio of SiO2, octadecylamine, ethanol, and H2O of 1:0.2:10:30 in the gel. The pH of the gel was adjusted to 12.0, and the mixture was stirred and aged at 35 °C for 24 hours. The resulting gel was filtered, washed with deionized water, and dried at 120 °C for 7 hours to obtain the precursor silicon material.

[0071] 1.31 g of tetrabutyl titanate, 2.04 g of triethylamine, 2.83 g of ethylenediamine, and 103.95 g of H2O were mixed, and precursor silicon material was added to achieve a molar ratio of SiO2, TiO2, (triethylamine + ethylenediamine), and water of 1:0.02:0.35:30. The mixture was crystallized at 160 °C for 72 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 400 °C for 10 hours to obtain a hierarchical porous titanium-silicon molecular sieve.

[0072] The XRD patterns of the above molecular sieves and Figure 1 Similarly, it is a mesoporous titanium silicate molecular sieve with an MFI topology. The N2 physisorption characterization results of this molecular sieve are similar to... Figure 2 Similarly, hysteresis loops were observed, confirming the presence of mesopores. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 28% of the total pore volume; pores with diameters between 2.0 and 5.0 nm accounted for 24%; pores with diameters between 5.0 and 20.0 nm accounted for 40%; and pores larger than 20.0 nm to 50.0 nm accounted for 8%. The average channel diameter was 2.8 nm, and the total pore volume was 0.31 cm³. 3 / g, micropore volume is 0.21cm³3 / g, specific surface area is 502m² 2 / g. The bulk density of the molecular sieve is 3.1 g / mL.

[0073]

Application Example 4

[0074] 1 g of the molecular sieve prepared in Example 4 was added to a fixed-bed reactor. A molar ratio of allyl chloride to H₂O₂ of 2.0:1 and a molar ratio of methanol to allyl chloride of 3.5:1 were introduced. The concentration of H₂O₂ was 60%, and the space velocity (H₂O₂) was 3.0 h⁻¹ (based on pure H₂O₂). -1 The reaction temperature is 50℃.

[0075] The reaction products were sampled and analyzed by gas chromatography. The results were as follows: ECH selectivity (based on allyl chloride) 94.45%, H2O2 conversion rate 90.85%, and H2O2 utilization rate 96.48%.

[0076]

Example 5

[0077] 11.55 g of silica, 70.84 g of anhydrous ethanol, and 3.83 g of tetradecylamine were mixed and stirred at room temperature. 46.5 g of H₂O₃ was added to achieve a molar ratio of SiO₂, tetradecylamine, ethanol, and H₂O of 1:0.1:8:100 in the gel. The pH of the gel was adjusted to 8.0, and the mixture was stirred and aged at 40 °C for 12 hours. The resulting gel was filtered, washed with deionized water, and dried at 120 °C for 10 hours to obtain the precursor silicon material.

[0078] 2.15 g of tetrabutyl titanate, 1.33 g of hexamethylenediamine, 0.56 g of n-butylamine, and 1.73 g of H₂O₅ were mixed, and precursor silicon material was added to achieve a molar ratio of SiO₂, TiO₂, (hexamethylenediamine + n-butylamine), and water of 1:0.033:0.10:15. The mixture was crystallized at 165 °C for 70 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 500 °C for 5 hours to obtain a hierarchical porous titanium-silicon molecular sieve.

[0079] The XRD patterns of the above molecular sieves and Figure 1 Similarly, it is a mesoporous titanium silicate molecular sieve with an MFI topology. The N2 physisorption characterization results of this molecular sieve are similar to... Figure 2 Similarly, hysteresis loops were observed, confirming the presence of mesopores. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 36% of the total pore volume; pores with diameters between 2.0 and 5.0 nm accounted for 21%; pores with diameters between 5.0 and 20.0 nm accounted for 36%; and pores larger than 20.0 nm to 50.0 nm accounted for 7%. The average channel diameter was 3.2 nm, and the total pore volume was 0.54 cm³.3 / g micropore volume is 0.30cm 3 / g, specific surface area is 498m² 2 / g. The bulk density of the molecular sieve is 3.6 g / mL.

[0080]

Application Example 5

[0081] 1 g of the molecular sieve prepared in Example 5 was added to a fixed-bed reactor. A cyclohexene:H₂O₂ molar ratio of 4.0:1 and an isopropanol:cyclohexene molar ratio of 1.0:1 were introduced. The H₂O₂ concentration was 15%, and the space velocity (H₂O₂) was 1.5 h⁻¹ (based on pure H₂O₂). -1 The reaction temperature is 45℃.

[0082] The reaction products were sampled and analyzed by gas chromatography. The results showed that the selectivity of cyclohexene epoxidation (based on cyclohexene) was 94.55%, the H2O2 conversion rate was 94.18%, and the effective utilization rate of H2O2 was 94.03%.

[0083]

Example 6

[0084] 11.55 g of silica, 26.57 g of anhydrous ethanol, and 7.66 g of tetradecylamine were mixed and stirred at room temperature. 11.85 g of H₂O₃ was then added to achieve a molar ratio of SiO₂, tetradecylamine, ethanol, and H₂O of 1:0.2:3:90 in the gel. The pH of the gel was adjusted to 9.5, and the mixture was stirred and aged at 17 °C for 18 hours. The resulting gel was filtered, washed with deionized water, and dried at 120 °C for 6 hours to obtain the precursor silicon material.

[0085] 2.16 g of tetrabutyl acetate, 1.02 g of tetrapropylammonium bromide, 2.53 g of n-butylamine, and 4.65 g of H₂O₃ were mixed, and a precursor silicon material was added to the mixture, so that the molar ratio of SiO₂, TiO₂, (tetrapropylammonium bromide + n-butylamine) and water in the mixture was 1:0.033:0.2:10. The mixture was crystallized at 170 °C for 48 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 500 °C for 5 hours to obtain a hierarchical porous titanium-silicon molecular sieve.

[0086] The XRD patterns of the above molecular sieves and Figure 1 Similarly, it possesses an MFI topology. The N2 physisorption characterization results of this molecular sieve are similar to... Figure 2Similarly, hysteresis loops were observed, confirming the presence of mesopores. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 27% of the total pore volume; pores with diameters between 2.0 and 5.0 nm accounted for 29%; pores with diameters between 5.0 and 20.0 nm accounted for 40%; and pores larger than 20.0 nm to 50.0 nm accounted for 4%. The average channel diameter was 3.7 nm, and the total pore volume was 0.55 cm³. 3 / g, micropore volume is 0.41cm³ 3 / g, specific surface area 545m² 2 / g. The bulk density of the molecular sieve is 3.4 g / mL.

[0087]

Application Example 6

[0088] 1 g of the molecular sieve prepared in Example 6 was added to a fixed-bed reactor. A propylene:H₂O₂ molar ratio of 4.5:1 and an ethanol:propylene molar ratio of 2.5:1 were introduced. The H₂O₂ concentration was 40%, and the space velocity (H₂O₂) was 2.5 h⁻¹ (based on pure H₂O₂). -1 The reaction temperature is 30℃.

[0089] The reaction products were sampled and analyzed by gas chromatography. The results showed that the selectivity of propylene oxide (based on propylene) was 96.51%, the conversion rate of H2O2 was 95.72%, and the effective utilization rate of H2O2 was 98.37%.

[0090]

Example 7

[0091] 11.55 g of silica, 44.28 g of anhydrous ethanol, and 10.68 g of dodecylamine were mixed and stirred at room temperature. 7.90 g of H₂O₂ was added to achieve a molar ratio of SiO₂, dodecylamine, ethanol, and H₂O of 1:0.30:5:60 in the gel. The pH of the gel was adjusted to 10.5, and the mixture was stirred and aged at 29 °C for 28 hours. The resulting gel was filtered, washed with deionized water, and dried at 120 °C for 6 hours to obtain the precursor silicon material.

[0092] 5.24 g of tetrabutyl titanate, 3.81 g of cyclohexylamine, and 69.30 g of H₂O were mixed, and precursor silicon material was added to achieve a molar ratio of SiO₂, TiO₂, cyclohexylamine, and water of 1:0.08:0.2:20. The mixture was crystallized at 175 °C for 48 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 500 °C for 5 hours to obtain a hierarchical porous titanium-silicon molecular sieve.

[0093] The XRD patterns of the above molecular sieves and Figure 1 Similarly, this is a mesoporous titanium silicate molecular sieve with an MFI topology. The N2 physisorption characterization results of this molecular sieve are similar to... Figure 2 Similarly, hysteresis loops were observed, confirming the presence of mesopores. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 32% of the total pore volume; pores with diameters between 2.0 and 5.0 nm accounted for 25%; pores with diameters between 5.0 and 20.0 nm accounted for 38%; and pores larger than 20.0 nm to 50.0 nm accounted for 5%. The average channel diameter was 3.4 nm, and the total pore volume was 0.41 cm³. 3 / g, micropore volume is 0.27cm³ 3 / g, specific surface area is 520m² 2 / g. The bulk density of the molecular sieve is 3.9 g / mL.

[0094]

Application Example 7

[0095] 1 g of the molecular sieve prepared in Example 7 was added to a fixed-bed reactor. A molar ratio of allyl chloride to H₂O₂ of 3.2:1 and a molar ratio of tert-butanol to allyl chloride of 2.8:1 were introduced. The concentration of H₂O₂ was 50%, and the space velocity (H₂O₂) was 2.0 h⁻¹ (based on pure H₂O₂). -1 The reaction temperature is 40℃.

[0096] The reaction products were sampled and analyzed by gas chromatography. The results were as follows: ECH selectivity (based on allyl chloride) 97.50%, H2O2 conversion rate 98.67%, and H2O2 utilization rate 92.24%.

[0097]

Example 8

[0098] 40.04 g of tetraethyl orthosilicate, 53.13 g of anhydrous ethanol, and 10.68 g of dodecylamine were mixed and stirred at room temperature. 42.55 g of H₂O₂ was added to achieve a molar ratio of SiO₂, dodecylamine, ethanol, and H₂O of 1:0.3:6:70 in the gel. The pH of the gel was adjusted to 9.5, and the mixture was stirred and aged at 32 °C for 30 hours. The resulting gel was filtered, washed with deionized water, and dried at 120 °C for 7 hours to obtain the precursor silicon material.

[0099] 6.55 g of tetrabutyl titanate, 2.19 g of isopropylamine, and 69.30 g of H₂O were mixed, and precursor silicon material was added to achieve a molar ratio of SiO₂, TiO₂, isopropylamine, and water of 1:0.10:0.20:20. The mixture was crystallized at 180 °C for 48 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 500 °C for 5 hours to obtain a hierarchical porous titanium-silicon molecular sieve.

[0100] The XRD patterns of the above molecular sieves and Figure 1Similarly, it is a mesoporous titanium silicate molecular sieve with an MFI topology. The N2 physisorption characterization results of this molecular sieve are similar to... Figure 2 Similarly, hysteresis loops were observed, confirming the presence of mesopores. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 31% of the total pore volume; pores with diameters between 2.0 and 5.0 nm accounted for 27%; pores with diameters between 5.0 and 20.0 nm accounted for 35%; and pores larger than 20.0 nm to 50.0 nm accounted for 7%. The average channel diameter was 3.3 nm, and the total pore volume was 0.38 cm³. 3 / g, micropore volume is 0.23cm³ 3 / g, specific surface area is 509m² 2 / g. The bulk density of the molecular sieve is 3.3 g / mL.

[0101]

Application Example 8

[0102] 1 g of the molecular sieve prepared in Example 8 was added to a fixed-bed reactor. The reactor was bubbled with butene:H₂O₂ at a molar ratio of 4.2:1, methanol:butene at a molar ratio of 2.7:1, and H₂O₂ at a concentration of 35%. The space velocity (H₂O₂) was 1.5 h⁻¹ (based on pure H₂O₂). -1 The reaction temperature is 45℃.

[0103] The reaction products were sampled and analyzed by gas chromatography. The results showed that the selectivity of epoxidized butene (based on butene) was 94.53%, the H2O2 conversion rate was 97.32%, and the effective utilization rate of H2O2 was 98.36%.

[0104]

Example 9

[0105] 40.04 g of tetraethyl orthosilicate, 53.13 g of anhydrous ethanol, and 20.50 g of hexadecylamine were mixed and stirred at room temperature. 42.55 g of H₂O₂ was added to achieve a molar ratio of SiO₂, hexadecylamine, ethanol, and H₂O of 1:0.5:6:70 in the gel. The pH of the gel was adjusted to 8.5, and the mixture was stirred and aged at 18 °C for 24 hours. The resulting gel was filtered, washed with deionized water, and dried at 120 °C for 9 hours to obtain the precursor silicon material.

[0106] 1.83 g of titanium tetrachloride, 1.28 g of tetrapropylammonium bromide, 1.95 g of trimethylamine, and 86.63 g of H₂O were mixed, and a precursor silicon material was added to the mixture, so that the molar ratio of SiO₂, TiO₂, (trimethylamine + tetrapropylammonium bromide) and water in the mixture was 1:0.05:0.25:25. The mixture was crystallized at 180 °C for 36 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 500 °C for 5 hours to obtain a hierarchical porous titanium-silicon molecular sieve.

[0107] The XRD patterns of the above molecular sieves and Figure 1 Similarly, it is a mesoporous titanium silicate molecular sieve with an MFI topology. The N2 physisorption characterization results of this molecular sieve are similar to... Figure 2 Similarly, hysteresis loops were observed, confirming the presence of mesopores. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 23% of the total pore volume; pores with diameters between 2.0 and 5.0 nm accounted for 30%; pores with diameters between 5.0 and 20.0 nm accounted for 41%; and pores larger than 20.0 nm to 50.0 nm accounted for 6%. The average channel diameter was 3.5 nm, and the total pore volume was 0.47 cm³. 3 / g, micropore volume is 0.32cm³ 3 / g, specific surface area is 475m² 2 / g. The bulk density of the molecular sieve is 3.7 g / mL.

[0108]

Application Example 9

[0109] 1 g of the molecular sieve prepared in Example 9 was added to a fixed-bed reactor. A mixture of allyl chloride and H₂O₂ molar ratios of 5.5:1 and acetone:allyl chloride molar ratios of 3.2:1 was introduced. The H₂O₂ concentration was 50%, and the space velocity (H₂O₂) was 2.2 h⁻¹ (based on pure H₂O₂). -1 The reaction temperature is 50℃.

[0110] The reaction products were sampled and analyzed by gas chromatography. The results showed that the ECH selectivity (based on allyl chloride) was 97.08%, the H2O2 conversion rate was 94.56%, and the H2O2 utilization rate was 99.27%.

[0111]

Example 10

[0112] 40.04 g of tetraethyl orthosilicate, 35.42 g of anhydrous ethanol, and 12.30 g of hexadecylamine were mixed and stirred at room temperature. 69.30 g of H₂O was added to achieve a molar ratio of SiO₂, hexadecylamine, ethanol, and H₂O of 1:0.3:4:20 in the gel. The pH of the gel was adjusted to 11.0, and the mixture was stirred and aged at 30 °C for 20 hours. The resulting gel was filtered, washed with deionized water, and dried at 120 °C for 8 hours to obtain the precursor silicon material.

[0113] 1.49 g of titanium trichloride, 1.44 g of ethylenediamine, 1.37 g of isopropylamine, and 103.95 g of H2O were mixed, and silicon precursor material was added to the mixture, so that the molar ratio of SiO2, TiO2, (ethylenediamine + isopropylamine) and water in the mixture was 1:0.05:0.25:30. The mixture was crystallized at 170 °C for 65 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 500 °C for 5 hours to obtain a hierarchical porous titanium-silicon molecular sieve.

[0114] The XRD patterns of the above molecular sieves and Figure 1 Similarly, it is a mesoporous titanium silicate molecular sieve with an MFI topology. The N2 physisorption characterization results of this molecular sieve are similar to... Figure 2 Similarly, hysteresis loops were observed, confirming the presence of mesopores. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 30% of the total pore volume; pores with diameters between 2.0 and 5.0 nm accounted for 16%; pores with diameters between 5.0 and 20.0 nm accounted for 47%; and pores larger than 20.0 nm to 50.0 nm accounted for 7%. The average channel diameter was 3.0 nm, and the total pore volume was 0.39 cm³. 3 / g, micropore volume is 0.34cm³ 3 / g, specific surface area is 541m² 2 / g. The bulk density of the molecular sieve is 3.6 g / mL.

[0115]

Application Example 10

[0116] 1 g of the molecular sieve prepared in Example 10 was added to a fixed-bed reactor. A cyclohexene:H₂O₂ molar ratio of 2.5:1 and a tert-butanol:cyclohexene molar ratio of 3.0:1 were introduced. The H₂O₂ concentration was 35%, and the space velocity (H₂O₂) was 1.7 h⁻¹ (based on pure H₂O₂). -1 The reaction temperature is 50℃.

[0117] The reaction products were sampled and analyzed by gas chromatography. The results showed that the selectivity of cyclohexene epoxidation (based on cyclohexene) was 94.47%, the H2O2 conversion rate was 94.03%, and the effective utilization rate of H2O2 was 97.26%.

[0118] Comparative Example 1

[0119] 38.50 g of 30% silica sol was added to 173.25 g of H2O and stirred at room temperature to achieve a SiO2:H2O molar ratio of 1:50 in the gel. The pH of the gel was adjusted to 9.0, and the gel was aged by stirring at 20 °C for 20 hours. The resulting gel was filtered, washed with deionized water, and dried at 120 °C for 5 hours to obtain the precursor silicon material.

[0120] 1.63 g of tetrabutyl titanate, 0.87 g of dimethylamine, 2.81 g of n-butylamine, and 69.30 g of H₂O were mixed, and precursor silicon material was added to achieve a molar ratio of SiO₂, TiO₂, (dimethylamine + n-butylamine), and water of 1:0.025:0.30:20. The mixture was crystallized at 180 °C for 48 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 500 °C for 5 hours to obtain titanium-silicon molecular sieves.

[0121] The above-mentioned molecular sieve was tested and no hysteresis loop was observed in the N2 adsorption-desorption curve. The modified molecular sieve has an average pore diameter of 2.7 nm and a total pore volume of 0.30 cm³. 3 / g, micropore volume is 0.21cm³ 3 / g. The measured pore volume was as follows: pores with a diameter less than 2.0 nm accounted for 55% of the total pore volume; pores with a diameter of 2.0–5.0 nm accounted for 38% of the total pore volume; pores with a diameter of 5.0–20.0 nm accounted for less than 4% of the total pore volume; and pores with a diameter greater than 20.0 nm to 50.0 nm accounted for 3% of the total pore volume. The specific surface area of ​​the titanium-silicon molecular sieve was 314 m². 2 / g. The bulk density of the molecular sieve is 5.6 g / mL.

[0122] 1 g of the modified molecular sieve was added to a fixed-bed reactor. A mixture of allyl chloride and H₂O₂ with a molar ratio of 2.0:1 and a methanol:allyl chloride molar ratio of 3.5:1 was introduced. The concentration of H₂O₂ was 60%, and the space velocity (H₂O₂) was 3.0 h⁻¹ (based on pure H₂O₂). -1 The reaction temperature is 50℃.

[0123] The reaction products were sampled and analyzed by gas chromatography. The results were as follows: ECH selectivity (based on allyl chloride) 90.34%, H2O2 conversion rate 90.24%, and H2O2 utilization rate 85.71%.

[0124] Comparative Example 2

[0125] 38.50 g of 30% silica sol, 53.13 g of anhydrous ethanol, and 7.45 g of n-octylamine were mixed and stirred at room temperature. 173.25 g of H2O was added to achieve a molar ratio of SiO2, n-octylamine, ethanol, and H2O of 1:0.3:6:50 in the gel. The pH of the gel was adjusted to 9.0, and the mixture was stirred and aged at 20°C for 20 hours. The resulting gel was filtered, washed with deionized water, and dried at 120°C for 5 hours to obtain the precursor silicon material.

[0126] 1.63 g of tetrabutyl titanate, 0.87 g of dimethylamine, 2.81 g of n-butylamine, and 69.30 g of H₂O were mixed, and precursor silicon material was added to achieve a molar ratio of SiO₂, TiO₂, (dimethylamine + n-butylamine), and water of 1:0.025:0.30:20. The mixture was crystallized at 180 °C for 48 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 500 °C for 5 hours to obtain titanium-silicon molecular sieves.

[0127] No hysteresis rings were observed in the molecular sieves synthesized using this method. The average pore diameter of the molecular sieves synthesized by this method is 2.6 nm, and the total pore volume is 0.26 cm³. 3 / g, micropore volume is 0.12cm³ 3 / g. The measured pore volume was 58% for pores smaller than 2.0 nm, 35% for pores between 2.0 and 5.0 nm, less than 5% for pores between 5.0 and 20.0 nm, and 2% for pores larger than 20.0 nm to 50.0 nm. The specific surface area of ​​the titanium-silicon molecular sieve was 352 m². 2 / g. The bulk density of the molecular sieve is 5.3 g / mL.

[0128] 1 g of the modified molecular sieve was added to a fixed-bed reactor. A mixture of allyl chloride and H₂O₂ with a molar ratio of 2.0:1 and a methanol:allyl chloride molar ratio of 3.5:1 was introduced. The concentration of H₂O₂ was 60%, and the space velocity (H₂O₂) was 3.0 h⁻¹ (based on pure H₂O₂). -1 The reaction temperature is 50℃.

[0129] The reaction products were sampled and analyzed by gas chromatography. The results were as follows: ECH selectivity (based on allyl chloride) 92.48%, H2O2 conversion rate 87.10%, and H2O2 utilization rate 77.94%.

[0130] Comparative Example 3

[0131] 38.50 g of 30% silica sol, 53.13 g of anhydrous ethanol, and 11.48 g of tetradecylamine were mixed and stirred at room temperature. 173.08 g of H2O was added to achieve a molar ratio of SiO2, tetradecylamine, ethanol, and H2O of 1:0.3:6:50 in the gel. The pH of the gel was adjusted to 9.0, and the mixture was stirred and aged at 20°C for 20 hours. The resulting gel was filtered, washed with deionized water, and dried at 120°C for 5 hours to obtain the precursor silicon material.

[0132] 1.63 g of tetrabutyl titanate, 3.41 g of n-propylamine, and 69.30 g of H₂O were mixed, and a precursor silicon material was added to the mixture, resulting in a molar ratio of SiO₂, TiO₂, n-propylamine, and water of 1:0.025:0.30:20. The mixture was crystallized at 180 °C for 48 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 500 °C for 5 hours to obtain a titanium-silicon molecular sieve.

[0133] The molecular sieve described above was tested and no hysteresis loop was observed in the N2 adsorption-desorption curve. The molecular sieve synthesized by this method has an average pore diameter of 2.5 nm and a total pore volume of 0.26 cm³. 3 / g, with a micropore volume of 0.12cm³. 3 / g. The measured pore volume was 61% for pores smaller than 2.0 nm, 35% for pores between 2.0 and 5.0 nm, less than 3% for pores between 5.0 and 20.0 nm, and 1% for pores larger than 20.0 nm to 50.0 nm. The BET specific surface area of ​​the titanium-silicon molecular sieve was 355 m² / g. 2 / g. The bulk density of the molecular sieve is 5.0 g / mL.

[0134] 1 g of the modified molecular sieve was added to a fixed-bed reactor. A mixture of allyl chloride and H₂O₂ with a molar ratio of 2.0:1 and a methanol:allyl chloride molar ratio of 3.5:1 was introduced. The concentration of H₂O₂ was 60%, and the space velocity (H₂O₂) was 3.0 h⁻¹ (based on pure H₂O₂). -1 The reaction temperature is 50℃.

[0135] The reaction products were sampled and analyzed by gas chromatography. The results were as follows: ECH selectivity (based on allyl chloride) 90.42%, H2O2 conversion rate 78.60%, and H2O2 utilization rate 84.87%.

[0136] Comparative Examples 4-6

[0137] Compared with Example 1 and Application Example 1 above, the only difference is that the calcination conditions for preparing titanium-silicon molecular sieves in Comparative Examples 4-6 were changed. The reaction conditions were the same as in Application Example 4, and the corresponding characterization results are shown in Table 1.

[0138] Table 1

[0139] Comparative Example 4 5 6 Firing temperature (°C) 650 350 600 Roasting time (hours) 3 11 3 ECH selectivity (based on allyl chloride) % 78.27 72.58 77.89 <![CDATA[H2O2 conversion rate %]]> 86.26 88.37 85.92 <![CDATA[Effective utilization rate of H2O2 %]]> 87.25 80.76 77.49 Does a hysteresis loop exist? none none none Average channel diameter (nm) 2.4 2.1 2.3 <![CDATA[Total pore volume (cm 3 / g)]]> 0.25 0.25 0.24 <![CDATA[Micropore volume (cm 3 / g)]]> 0.15 0.12 0.12 <![CDATA[BET specific surface area (m 2 / g)]]> 250 246 281 % of total pore volume with a pore size less than 2.0 nm 62 55 63 Pore ​​diameter of 2.0–5.0 nm accounts for % of total pore volume. 24 24 20 Pore ​​diameter of 5.0–20.0 nm as a percentage of total pore volume 14 17 12 % of total pore volume greater than 20.0 nm to 50.0 nm 0 4 5 Molecular sieve bulk density (g / mL) 5.2 5.7 5.9

[0140] The embodiments described above are merely detailed descriptions of the technical solutions of the present invention, but the present invention is not limited to the above embodiments, that is, the present invention does not depend on the steps described in the above embodiments to be implemented. In summary, any improvements made to the present invention by those skilled in the art, including the substitution of the raw materials and additives described in the present invention, the selection of specific implementation methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing an epoxide compound by olefin epoxidation, wherein H2O2 is contacted with an olefin in a solvent in the presence of a catalyst, the catalyst being a hierarchical-pore titanium silicalite molecular sieve with a bulk density of 3.0-4.0 g / mL. The pore distribution of the multi-level pore titanosilicate molecular sieve is as follows: the pore volume of pores with a pore size less than 2.0 nm accounts for 20% to 40% of the total pore volume, the pore volume of pores with a pore size of 2.0 to 5.0 nm accounts for 10% to 30% of the total pore volume, the pore volume of pores with a pore size of 5.0 to 20.0 nm accounts for 25% to 50% of the total pore volume, and the pore volume of pores with a pore size greater than 20.0 to 50.0 nm accounts for less than 10% of the total pore volume; the specific surface area of the multi-level pore titanosilicate molecular sieve is 450 to 550 m 2 / g, the total pore volume is 0.31 to 0.55 cm 3 / g, the micropore volume is 0.20 to 0.45 cm 3 / g, the multi-level pore includes micropores and mesopores, the micropores refer to pores with a pore size of 0.5 to 0.8 nm, and the mesopores refer to pores with a pore size of 2.0 to 50.0 nm.

2. The method of claim 1, wherein, The olefin is at least one selected from the group consisting of propylene, chloropropylene, butene and cyclohexene.

3. The method of claim 1, wherein, The solvent is at least one selected from the group consisting of acetone, methanol, ethanol, isopropanol, tert-butanol and acetonitrile.

4. The method of claim 1, wherein, The mass concentration of H2O2 is 15%-60%.

5. The method of claim 1, wherein, The molar ratio of the olefin to H2O2 is 2.0-6.0:1, and the molar ratio of the solvent to the olefin is 1.0-4.0:

1.

6. The method of claim 1, wherein, The reaction temperature is 30-60°C, the liquid hourly space velocity of H2O2 is 0.5-3.0 h -1 .

7. The method of claim 1, wherein, The hierarchical-pore titanium silicalite molecular sieve has a pore volume of 4%-9% of the total pore volume for pores with a pore size of greater than 20.0-50.0 nm.

8. The method of claim 1, wherein, The average pore size of the hierarchical-pore titanium silicalite molecular sieve is 2.5-3.8 nm.

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